MESO: Mesoscale Discussion 1564

ACUS11 KWNS 212243
SWOMCD
SPC MCD 212243
NDZ000-220045-

MESOSCALE DISCUSSION 1564
NWS STORM PREDICTION CENTER NORMAN OK
0543 PM CDT SAT JUL 21 2007

AREAS AFFECTED...WRN THROUGH N CNTRL ND

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 212243Z - 220045Z

WRN ND IS BEING MONITORED FOR THUNDERSTORM DEVELOPMENT. PRIMARY
UNCERTAINTY IS WHETHER OR NOT STORMS WILL INITIATE. HOWEVER...IF
STORMS DEVELOP THEY WILL BE CAPABLE OF PRODUCING ISOLATED LARGE HAIL
AND DAMAGING WIND. TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.

EARLY THIS EVENING A COLD FRONT STRETCHES FROM SERN SASKATCHEWAN
SWWD THROUGH NERN MT. PRE-FRONTAL TROUGH EXTENDS FROM A WEAK SURFACE
LOW OVER WRN ND SWD THROUGH SWRN ND AND WRN SD. WARM FRONT EXTENDS
SEWD FROM THE LOW THROUGH SWRN ND AND CNTRL SD. LOW LEVEL DEWPOINTS
IN THE UPPER 60S HAVE ADVECTED NWD THROUGH PRE-FRONTAL WARM SECTOR
BENEATH 8+ MID LEVEL LAPSE RATES. THIS HAS CONTRIBUTED TO MLCAPE
FROM 3500 TO 4000 J/KG OVER WRN AND CNTRL ND. WV IMAGERY SHOWS A
SHORTWAVE TROUGH EJECTING NEWD INTO SASKATCHEWAN WITH WEAK FORCING
AND LIMITED CONVERGENCE FARTHER SE ALONG BOUNDARIES OVER WRN AND
NWRN ND. HOWEVER...LATEST OBJECTIVE ANALYSIS SUGGESTS CONVECTIVE
INHIBITION MAY HAVE WEAKENED SUFFICIENTLY FOR STORMS TO INITIATE
ALONG FRONT OR PRE-FRONTAL TROUGH OVER PARTS OF WRN ND. SOME
BOUNDARY LAYER CUMULUS IS DEVELOPING VICINITY OF THE FRONT AND
PRE-FRONTAL TROUGH OVER NWRN AND WRN ND. DEEP SHEAR OF 30-40 KT WILL
SUPPORT SUPERCELL STRUCTURES IF STORMS MANAGE TO DEVELOP WITH
ISOLATED DAMAGING WIND AND LARGE HAIL THE MAIN THREATS.

.DIAL.. 07/21/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...BIS...

47360070 47120248 47930349 48840380 48900146 48310038

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